Tilt-in-space or tilt-and-recline wheelchairs are known. See, for example, the survey article titled "Tilt & Recline: A Balance of Cost and Consumer Need", which appeared in Team Rehab Report, Miramar Communications, Inc., April, 1996 (ISSN 1053-5926). A consensus of opinion in the design of such chairs appears to indicate that cost and mechanical adaptability are key factors needing improvement to satisfy current needs of patients who require such chairs for mobility.
Wheelchair bound patients, who spend most of their day in fixed-in-space seating, or in seating having limited ability to recline, can develop body sores, aches and pains and general malaise resulting from the pressure of sitting in a single position for extended periods of time. "Tilt-in-space" is an option that is available on some higher priced wheelchairs that allows the frame and attached seating system to be tilted or rotated in space. This is often needed to better position a patient who is hypotonic by allowing gravity to help keep him/her sitting upright. This feature is also often used in reducing sitting pressures by tilting and thus transferring pressure from the seat surface to the back surface in an effort to prevent decubitus ulcers in patients who cannot otherwise effect weight shifts.
Problems associated with current tilt-in-space wheelchairs may include:
Inability to fold the wheelchair in the conventional way for transport in a vehicle; PA1 High cost; and PA1 Weight.
Previous efforts have been made to provide wheelchair assemblies having adjustable seating which are also economically feasible, and are described in previous patents. For example, U.S. Pat. No. 5,292,144 describes a conversion kit for standard wheelchairs whereby a wheelchair with a stationary fixed seat can be retrofitted with a tiltable seat having a reclinable back. The seat and back may be separately adjusted by extendible, lockable adjusters and the seat and back apparatus is mountable upon conventional wheelchair constructions. See also the patents described therein. The apparatus of that invention must be removed in order to transport the chair from one site to another, and must be reassembled at the new location.
U.S. Pat. No. 4,565,385 discloses a tiltable supporting wheelchair having a tilting mechanism with front support wheels which pivot downwardly and outwardly engaging the floor and raising the front of the wheelchair, thereby tilting it backwardly. The tilting mechanism includes a cross-frame pivotably attached to the frame of the wheelchair and activated by movement of an attached arm. The arm is controlled by a rod leading to a pivotable plate which is connected to a lever on the side of the wheelchair by a linkage. Upon movement of the lever, the linkage rotates the plate, moving the arm and cross-frame to extend or retract the front wheels. A locking mechanism prevents accidental movement of the lever. Rear supports extend behind the wheelchair and engage the floor upon the front wheels being pivoted to their furthest point forward. This device also must be disassembled for transporting it from one site to another. Furthermore, when the tilt feature of this device is activated, the legrests simultaneously elevate, resulting in knee extension which is undesirable in most situations. The general purpose of a "tilt-in-space" chair is to rotate the patient posteriorly while at the same time maintaining 90 degree angles at the hips and knees. This prior apparatus does not maintain all relative positioning angles of the patient's body and limbs upon tilting of the chair.